As semiconductor device become more highly integrated, a capacitor having sufficient capacitance in a limited area is required. The capacitance of a capacitor is proportional to a surface area of an electrode and a dielectric constant of dielectric film and is inversely proportional to an equivalent oxide thickness of the dielectric film. In methods for increasing the capacitance of capacitor in a limited area, a surface area of electrode may be increased by forming a capacitor of a three dimensional structure, an equivalent oxide thickness of dielectric film may be reduced and a dielectric film having a high dielectric constant may be used.
In methods that increase the surface area of electrode, a height of lower electrode (or a storage electrode) may be increased, an effective surface area of lower electrode using a hemi-spherical grain (HSG) may be enlarged and an inside area and an outside area of cylinder using one cylinder storage (OCS) electrode may be used. As a dielectric film having a high dielectric constant, there may be a metal oxide film such as TiO2 and Ta2O5 or a ferroelectric of perovskite structure.